Abstract The Faidja Formation displays mixed siliciclastic-carbonate deposits distributed in three members, which are organised from bottom to top as follows: the Clayey Sandstone Faidja Member; the Clayey Limestone Bel Aoura Member and the Sandy Claystone Douaouda Member. Sedimentological data indicate the evolution of a subsiding marine environment from the shelf edge to the lower shoreface, sporadically dominated by storms. New age based on recently collected ammonite fauna allowed us to update the age of the Faidja Formation as Early-Late Kimmeridgian. Ichnological analysis reveals the occurrence of abundant and diverse invertebrate trace fossils, grouped in four ichnoassociations. Ichnoassociation -A- coincides with the lowermost part of the Clayey Sandstone Faidja Member; it is distinguished by a combination of pre-graphoglyptids and post-depositional traces, ascribed to the distal Cruziana ichnofacies transitional to the Nereites ichnofacies, which indicates a lower offshore zone to shelf edge environment characterised by a low-oxygenated period (anoxic event), frequent storm events and nutrient frequency. Ichnoassociation -B- occupies the middle and upper parts of the Clayey Sandstone Faidja Member, it is characterised by an abundance of post-depositional traces, corresponding to the archetypal Cruziana ichnofacies that indicates a lower to transitional offshore environment with short phases of low hydrodynamic energy. Ichnoassociation -C- corresponds to the Clayey Limestone Bel Aoura Member that coincides with a drastic facial change and depositional conditions; this association documents a proximal Cruziana ichnofacies, and indicates an upper to transitional offshore zone as a depositional environment. Finally, ichnoassociation -D- coincides with the Sandy Claystone Douaouda Member; it is ascribed to the proximal Cruziana ichnofacies, indicating a lower shoreface environment. The combined sedimentological and ichnological data indicates a relatively subsiding platform with shallowing upwards corresponding to distal, archetypal and proximal Cruziana ichnofacies, respectively.

中文翻译：

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上侏罗统 Faïdja 组（阿尔及利亚西北部）：生物地层学、地层学和沉积学

摘要 Faidja 组显示混合硅质碎屑-碳酸盐沉积物分布在三个段，从下到上排列如下：Clayey 砂岩 Faidja 段；Clayey Limestone Bel Aoura 成员和 Sandy Claystone Douaouda 成员。沉积学数据表明从陆架边缘到下岸面的下沉海洋环境的演变，偶尔以风暴为主。基于最近收集的菊石动物群的新时代使我们能够将 Faidja 组的年龄更新为早晚金默里吉纪。Ichnological 分析揭示了丰富多样的无脊椎动物痕迹化石的出现，分为四个 ichnoassociations。Ichnoassociation -A- 与 Clayey 砂岩 Faidja 成员的最下部重合；它的特点是结合了前石墨烯和沉积后痕迹，归因于向 Nereites 地层过渡的远端 Cruziana 地层相，这表明以低氧期（缺氧事件）为特征的低离岸带到陆架边缘环境，频繁的风暴事件和养分频率。Ichnoassociation -B- 位于 Clayey 砂岩 Faidja 段的中部和上部，其特征是沉积后痕迹丰富，对应于原型 Cruziana 地层相，表明具有低水动力能量短相的低到过渡近海环境. Ichnoassociation -C- 对应于 Clayey Limestone Bel Aoura 成员，与剧烈的面部变化和沉积条件相吻合；该关联记录了近端 Cruziana 地层相，并表明作为沉积环境的上层至过渡近海带。最后，ichnoassociation -D- 与 Sandy Claystone Douaouda 成员重合；它归因于近端 Cruziana 地层相，表明较低的滨面环境。组合的沉积学和地质学数据表明一个相对下沉的平台，向上变浅，分别对应于远端、原型和近端 Cruziana 地层相。